Abstract : This study aimed to determine metabolic and respiratory adaptations during intense exercise and improvement of long-sprint performance following six sessions of long-sprint training. Nine subjects performed before and after training (1) a 300-m test, (2) an incremental exercise up to exhaustion to determine the velocity associated with maximal oxygen uptake (v-VO 2max), (3) a 70-s constant exercise at intensity halfway between the v-VO 2max and the velocity performed during the 300-m test, followed by a 60-min passive recovery to determine an individual blood lactate recovery curve fitted to the bi-exponential time function: La t ð Þ ¼ La 0 ð Þ þ A 1 ð1 À e Àc 1 t Þ þ A 2 ð1 À e Àc 2 t Þ, and blood metabolic and gas exchange responses. The training program consisted of 3–6 repetitions of 150–250 m interspersed with rest periods with a duration ratio superior or equal to 1:10, 3 days a week, for 2 weeks. After sprint training, reduced metabolic disturbances, characterized by a lower peak expired ventilation and carbon dioxide output, in addition to a reduced peak lactate (P \ 0.05), was observed. Training also induced significant decrease in the net amount of lactate released at the beginning of recovery (P \ 0.05), and significant decrease in the net lactate release rate (NLRR) (P \ 0.05). Lastly, a significant improvement of the 300-m performance was observed after training. These results suggest that long-sprint training of short durations was effective to rapidly prevent metabolic disturbances, with alterations in lactate accumulation and gas exchange, and improvement of the NLRR. Furthermore, only six long-sprint training sessions allow long-sprint performance improvement in active subjects.